Endoscope assembly with a polarizing filter

ABSTRACT

An endoscope includes an imaging device, a first polarizing filter disposed in front of the imaging device, a light source, and a second polarizing filter disposed in front of the light source.

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 11/673,470, filed Feb. 9, 2007, the entiredisclosure of which is incorporated herein by reference; U.S. patentapplication Ser. No. 11/673,470 claims the benefit of U.S. ProvisionalPatent Application No. 60/772,442, filed Feb. 9, 2006; and U.S. patentapplication Ser. No. 11/673,470 is a continuation-in-part application ofU.S. patent application Ser. No. 11/672,020, filed Feb. 6, 2007, of U.S.patent application Ser. No. 11/626,189, filed Jan. 23, 2007, of U.S.patent application Ser. No. 11/609,838, filed Dec. 12, 2006, of U.S.patent application Ser. No. 11/215,660. filed Aug. 29, 2005, and of U.S.patent application Ser. No. 11/030,559, filed Jan. 5, 2005.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an endoscope assembly with a polarizingfilter.

BACKGROUND OF THE INVENTION

A conventional endoscope is a medical device comprising a flexible tube,and a camera and a light source mounted on the distal end of theflexible tube. The endoscope is insertable into an internal body cavitythrough a body orifice to examine the body cavity and tissues fordiagnosis. The tube of the endoscope has one or more longitudinalchannels, through which an instrument can reach the body cavity to takesamples of suspicious tissues or to perform other surgical proceduressuch as polypectomy.

There are many types of endoscopes, and they are named in relation tothe organs or areas with which they are used. For example, gastroscopesare used for examination and treatment of the esophagus, stomach andduodenum; colonoscopes for the colon; bronchoscopes for the bronchi;laparoscopes for the peritoneal cavity; sigmoidoscopes for the rectumand the sigmoid colon; arthroscopes for joints; cystoscopes for theurinary bladder, and angioscopes for the examination of blood vessels.

Each endoscope has a single forward viewing camera mounted at the distalend of the flexible tube to transmit an image to an eyepiece or videocamera at the proximal end. The camera is used to assist a medicalprofessional in advancing the endoscope into a body cavity and lookingfor abnormalities. The camera provides the medical professional with atwo-dimensional view from the distal end of the endoscope. To capture animage from a different angle or in a different portion, the endoscopemust be repositioned or moved back and forth. Repositioning and movementof the endoscope prolongs the procedure and causes added discomfort,complications, and risks to the patient. Additionally, in an environmentsimilar to the lower gastro-intestinal tract, flexures, tissue folds andunusual geometries of the organ may prevent the endoscope's camera fromviewing all areas of the organ. The unseen area may cause a potentiallymalignant (cancerous) polyp to be missed.

This problem can be overcome by providing an auxiliary camera and anauxiliary light source. The auxiliary camera and light source can beoriented to face the main camera and light source, thus providing animage of areas not viewable by the endoscope's main camera. Thisarrangement of cameras and light sources can provide both front and rearviews of an area or an abnormality. In the case of polypectomy where apolyp is excised by placing a wire loop around the base of the polyp,the camera arrangement allows better placement of the wire loop tominimize damage to the adjacent healthy tissue.

Since the main camera and light source face the auxiliary camera andlight source, the main light source interferes with the auxiliarycamera, and the auxiliary light source interferes with the main camera.Light interference is the result of the light from a light source beingprojected directly onto the lens of a camera. This may cause lightglare, camera blooming, or over saturation of light, resulting ininferior image quality.

Additionally, because of space constraint, the auxiliary camera andauxiliary light source are typically smaller than the main camera andmain light source and use different technologies. Different types ofcameras often require different levels of illumination. For example, themain camera generally requires a higher level of illumination and needsa more powerful light source. As a result, the auxiliary camera is oftenexposed to a significant amount of glare caused by the powerful mainlight source.

Therefore, there is a need to reduce or prevent light interferencebetween the main camera and main light source and the auxiliary cameraand auxiliary light source.

SUMMARY OF THE INVENTION

It is an object of this invention to address the problem of lightinterference involving the use of imaging devices and light sources forendoscopes. According to one aspect of the invention, the solution liesin the use of one or more polarizing filters including one or morelinear or circular polarizing filters.

In accordance with one aspect of the invention, an endoscope assemblyincludes an imaging device, a light source, and a circular polarizingfilter disposed in front of the light source. The circular polarizingfilter may be a first circular polarizing filter, and the endoscopeassembly may further include a second circular polarizing filterdisposed in front of the imaging device. The first and second circularpolarizing filters may have opposite orientations. Preferably, each ofthe opposite polarizing filters includes a retarder, and the retardersof the opposite polarizing filters face each other. Additionally, thelight source may be positioned to illuminate a field of view of theimaging device and may face the imaging device.

In accordance with another aspect of the invention, an endoscopeassembly includes a light source and a circular polarizing filterdisposed in front of the imaging device. The circular polarizing filtermay be a first circular polarizing filter, and the endoscope assemblymay further include a second circular polarizing filter disposed infront of the light source. Preferably, the first and second circularpolarizing filters have opposite orientations. Each of the oppositepolarizing filters may include a retarder, and the retarders of theopposite polarizing filters face each other. Additionally, the lightsource may face the imaging device.

In accordance with yet another aspect of the invention, an endoscopeassembly includes an imaging device, a light source, and a circularpolarizing filter disposed in front of both the imaging device and thelight source. The endoscope assembly may further include a cap, and thecircular polarizing filter is disposed on the cap.

In accordance with yet another aspect of the invention, an endoscopeassembly includes an imaging device, a first circular polarizing filterdisposed in front of the imaging device, a light source, and a secondcircular polarizing filter disposed in front of the light source.Preferably, the first and second circular polarizing filters haveopposite orientations. Each of the first and second polarizing filtersmay include a retarder, and the retarders of the first and secondpolarizing filters face each other. Preferably, the imaging device is afirst imaging device and the light source is a first light source, andthe endoscope assembly includes a second imaging device, a thirdcircular polarizing filter disposed in front of the second imagingdevice, a second light source, and a fourth circular polarizing filterdisposed in front of the second light source. Preferably, the third andfourth circular polarizing filters have opposite orientations. Each ofthe third and fourth polarizing filters may include a retarder and theretarders of the third and fourth polarizing filters may face eachother. In some preferred embodiments, the first light source faces thefirst imaging device, and the second light source faces the secondimaging device. Preferably, the second light source is positioned toilluminate a field of view of the first imaging device, and the firstlight source is positioned to illuminate a field of view of the secondimaging device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of an endoscope with an imaging assemblyaccording to one embodiment of the present invention.

FIG. 2 shows a perspective view of the distal end of an insertion tubeof the endoscope of FIG. 1 with a polarizer cap.

FIG. 3 shows a perspective back view of the polarizer cap of FIG. 2.

FIG. 4 shows a perspective view of the imaging assembly shown in FIG. 1.

FIG. 5 shows a perspective view of the distal ends of the endoscope andimaging assembly of FIG. 1 with a cross-sectional view of the lensbarrel of the imaging assembly.

FIG. 6 shows a cross-sectional view of a peritoneal cavity with multipleendoscopes.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 illustrates a first exemplary endoscope 10 of the presentinvention. This endoscope 10 can be used in a variety of medicalprocedures in which imaging of a body tissue, organ, cavity or lumen isrequired. The types of procedures include, for example, anoscopy,arthroscopy, bronchoscopy, colonoscopy, cystoscopy, EGD, laparoscopy,and sigmoidoscopy.

The endoscope 10 of FIG. 1 includes an insertion tube 12 and an imagingassembly 14, a section of which is housed inside the insertion tube 12.As shown in FIG. 2, the insertion tube 12 has two longitudinal channels16. In general, however, the insertion tube 12 may have any number oflongitudinal channels. An instrument can reach the body cavity toperform any desired procedures, such as to take samples of suspicioustissues or to perform other surgical procedures such as polypectomy. Theinstruments may be, for example, a retractable needle for druginjection, hydraulically actuated scissors, clamps, grasping tools,electrocoagulation systems, ultrasound transducers, electrical sensors,heating elements, laser mechanisms and other ablation means. In someembodiments, one of the channels can be used to supply a washing liquidsuch as water for washing. Another or the same channel may be used tosupply a gas, such as CO₂ or air into the organ. The channels 16 mayalso be used to extract fluids or inject fluids, such as a drug in aliquid carrier, into the body. Various biopsy, drug delivery, and otherdiagnostic and therapeutic devices may also be inserted via the channels16 to perform specific functions.

The insertion tube 12 preferably is steerable or has a steerable distalend region 18 as shown in FIG. 1. The length of the distal end region 18may be any suitable fraction of the length of the insertion tube 12,such as one half, one third, one fourth, one sixth, one tenth, or onetwentieth. The insertion tube 12 may have control cables (not shown) forthe manipulation of the insertion tube 12. Preferably, the controlcables are symmetrically positioned within the insertion tube 12 andextend along the length of the insertion tube 12. The control cables maybe anchored at or near the distal end 36 of the insertion tube 12. Eachof the control cables may be a Bowden cable, which includes a wirecontained in a flexible overlying hollow tube. The wires of the Bowdencables are attached to controls 20 in the handle 22. Using the controls20, the wires can be pulled to bend the distal end region 18 of theinsertion tube 12 in a given direction. The Bowden cables can be used toarticulate the distal end region 18 of the insertion tube 12 indifferent directions.

As shown in FIG. 1, the endoscope 10 may include a control handle 22connected to the proximal end 24 of the insertion tube 12. Preferably,the control handle 22 has one or more ports and/or valves (not shown)for controlling access to the channels 16 of the insertion tube 12. Theports and/or valves can be air or water valves, suction valves,instrumentation ports, and suction/instrumentation ports. As shown inFIG. 1, the control handle 22 may additionally include buttons 26 fortaking pictures with an imaging device on the insertion tube 12, theimaging assembly 14, or both.

The proximal end 28 of the control handle 22 may include an accessoryoutlet 30 (FIG. 1) that provides fluid communication between the air,water and suction channels and the pumps and related accessories. Thesame outlet 30 or a different outlet can be used for electrical lines tolight and imaging components at the distal end of the endoscope 10.

As shown in FIG. 2, the endoscope 10 also includes a main imaging device32 and main light sources 34, both of which are disposed at the distalend 36 of the insertion tube 12, and a polarizer cap 38 that is adaptedto be mounted on the distal end 36 of the insertion tube 12 to cover themain imaging device 32 and main light sources 34. FIG. 2 shows thepolarizer cap 38 removed from the distal end 36 of the insertion tube12, and FIG. 5 shows the polarizer cap 38 mounted on the distal end 36of the insertion tube 12.

The main imaging device 32 at the distal end 36 of the insertion tube 12may include, for example, a lens, single chip sensor, multiple chipsensor or fiber optic implemented devices. The main imaging device 32,in electrical communication with a processor and/or monitor, may providestill images or recorded or live video images. The light sources 34 maybe light emitting diodes (LEDs) or fiber optical delivery of light froman external light source. The light sources 34 preferably areequidistant from the main imaging device 32 to provide evenillumination. The intensity of each light source 34 can be adjusted toachieve optimum imaging. The circuits for the main imaging device 32 andlight sources 34 may be incorporated into a printed circuit board (PCB).As shown in FIG. 2, the insertion tube 12 has a channel 40 for supplyinga liquid such as water for cleaning the lenses of the main imagingdevice 32 and the light sources 34.

The polarizer cap 38, as shown in FIGS. 2 and 3, includes a cylindricalsidewall 42, an end wall 44, and polarizing filters 46, 48 mounted onthe end wall 44. The cylindrical sidewall 42 and end wall 44 may form anintegral part that is made by injection molding of a suitablebiocompatible material such as medical grade plastics. The end wall 44preferably has an opening 50 for accommodating the polarizing filter 46for the main imaging device 32. The opening 50 may have any arrangementsuitable for retaining the polarizing filter 46. For example, theopening 50 may have a recessed lip for receiving the polarizing filter46. The polarizing filter 46 can be placed in the recessed lip and fixedthere by adhesive bonding or by a mechanical snap fit.

The end wall 44 preferably has an opening 52 for accommodating thepolarizing filter 48 for each of the light sources 34. The opening 52may have any arrangement suitable for retaining the polarizing filter48. One example of such suitable arrangement is the recessed lipdescribed above. The end wall 44 preferably has an opening 54 for eachof the instrument channels 16 so that the cap 38 does not block thechannels 16.

The end wall 44 may further include an opening 56 for the channel 40 forsupplying a liquid to clean the lenses of the imaging device 32 and thelight sources 34. Preferably, the cap 38 has one or more features thatallow liquid from the channel 40 to reach over the cap 38 to clean theexterior surfaces of polarizing filters 46, 48. For example, the endwall 44 of the cap 38 may be sufficiently thin to allow the liquid fromthe channel 40 to reach over the cap 38 to clean the exterior surfacesof polarizing filters 46, 48. Alternatively, the cap 38 may havevariable thickness and/or angled features that allow liquid from thechannel 40 to reach the polarizing filters 46, 48. Furthermore, the cap38 may have a ramp, plate or channel that allows liquid from the channel40 to reach the polarizing filters 46, 48. The locations, configurationsand sizes of the openings 50, 52, 54, 56 preferably correspond to thelocations, configurations and sizes of the main imaging device 32, lightsources 34, channels 16, and clean liquid channel 40, respectively.

As shown in FIG. 3, the cap 38 preferably has a ring 58 located aroundthe inner perimeter of the cap 38. The ring 58 helps secure the cap 38to the distal end region of the insertion tube 12. In a preferredembodiment, the ring 58 is made from a compressive material such assilicon. Alternatively, the ring 58 can be made from other compressivematerials, such as compressive rubbers, polymers and/or foams. The ring58 may be attached the inner perimeter of the cap 38 by any suitablemeans such as adhesive bonding, mechanical over molding, or plastic snapfeatures.

The inside diameter of the ring 58 preferably is slightly smaller thanthe outer diameter of the insertion tube 12 so that the ring 58 canapply a compressive force to the outer surface of the insertion tube 12.This compressive force preferably is sufficient to create the necessaryfriction force to ensure that the cap 38 remains in the same positionand orientation during a medical procedure, yet to allow the cap 38 tobe slide on and off of the insertion tube 12 without difficulty.

Alternatively, the cap 38 may have any other type of arrangement forattachment to the insertion tube 12. For example, the cap 38 may haveclasps which snap on to the insertion tube 12. In some embodiments, theattachment may be similar to the way in which a suction cap forendoscopic mucosal resection is attached to a colonoscope, as is wellknown in the art.

The terms “polarizing filter” and “polarizer” as used in thisspecification refer to any device that blocks one or more components oflight while allowing one or more other components to pass through. Insome cases, polarizing filters may be made from a material that blockslight waves traveling in all planes from passing through the filterexcept for light waves propagating in one specific plane of orientation,often referred to as the plane of polarization or the plane oftransmission. Polarizing filters may be constructed using varioustechniques that use light absorption, reflection, scattering orbirefringence to block light from passing through the filter that is notorientated parallel with the plane of transmission.

When one polarizing filter is placed in front of another polarizingfilter and non-coherent natural white light is passed through the twopolarizing filters, the amount of light that passes through the twopolarizing filters is proportional to the relative angle of orientationof the two filters. This is because when the polarization plane of thetwo filters is at the same angle of orientation, the majority of lightwaves in the plane of transmission will pass through both filters. Asone of the filters is rotated, light that is polarized by the firstfilter is then attenuated or blocked by the second filter. The maximumamount of light reduction or extinction occurs when the polarizingplanes of the two filters are orientated at 90° relative to each other.It is common to find polarizing filters that when orientated at 90°provide 99% or greater extinction of light transmission.

Light reduction or extinction by way of a combination of two polarizingfilters can similarly be achieved using circular polarizing filters,such as a combination of a left-hand polarizing filter and a right-handpolarizing filter (i.e., a combination of a polarizing filter thatrotates the light clockwise and a polarizing filter that rotates thelight counter-clockwise).

A circular polarizing filter converts unpolarized light to circularlypolarized light. Just as a linear polarizing filter transmits light onlyin one plane of polarization, a circular polarizer transmits light inonly one particular circular orientation of polarization. A circularpolarizing filter often has a composite structure that includes a linearpolarizing filter and a quarter wave retarder. The retarder axis isoriented at 45° with respect to the axis of the linear polarizingfilter. As incident light passes through the composite it is convertedto circularly polarized light.

When light is transmitted through a first right-hand circular polarizingfilter (which, for instance, is constructed as a linear polarizingfilter followed by a quarter wave retarder orientated at 45° withrespect to the axis of the linear polarizing filter) and then istransmitted to a second left-hand circular polarizing filter (which, forinstance, is constructed as a quarter wave retarder followed by a linearpolarizing filter with the retarder oriented at −45° with respect to theaxis of the linear polarizing filter), almost no light will pass throughthe second left-hand circular polarizing filter. This is because thefirst circular polarizing filter spins the light in one direction andthe second polarizing filter only allows light that is spun in theopposite direction to pass through.

As shown in FIGS. 4 and 5, the imaging assembly 14 may include a tubularbody 60, a handle 62 connected to the proximal end 61 of the tubularbody 60, an auxiliary imaging device 64, a link 66 that providesphysical and/or electrical connection between the auxiliary imagingdevice 64 to the distal end 68 of the tubular body 60, and an auxiliarylight source 70 (FIG. 5).

As shown in FIG. 5, the imaging assembly 14 is used to provide anauxiliary imaging device at the distal end of the endoscope 10. To thisend, the imaging assembly 14 is placed inside one of the channels 16 ofthe endoscope's insertion tube 12 with its auxiliary imaging device 64disposed beyond the distal end 36 of the insertion tube 12. This can beaccomplished by first inserting the distal end of the imaging assembly14 into the insertion tube's channel 16 from the endoscope's handle 18and then pushing the imaging assembly 14 further into the assembly 14until the auxiliary imaging device 64 and link 66 of the imagingassembly 14 are positioned outside the distal end 36 of the insertiontube 12 as shown in FIG. 5.

As shown in FIG. 5, the auxiliary imaging device 64 may include a lensbarrel 72 having one or more lenses 74, an imaging sensor, and a printedcircuit board (PCB). The imaging sensor may be an electronic devicewhich converts light incident on photosensitive semiconductor elementsinto electrical signals. The imaging sensor may detect either color orblack-and-white images. The signals from the imaging sensor can bedigitized and used to reproduce an image that is incident on the imagingsensor. Two commonly used types of image sensors are Charge CoupledDevices (CCD) such as a VCC-5774 produced by Sanyo of Osaka, Japan andComplementary Metal Oxide Semiconductor (CMOS) camera chips such as anOVT 6910 produced by OmniVision of Sunnyvale, Calif.

The endoscope 10 preferably includes a polarizing filter 76 placed infront of the auxiliary imaging device 64. The polarizing filter 76 maybe placed inside the lens barrel 72. Alternatively, the polarizingfilter 76 may be placed directly onto the image sensor itself, orincorporated at various other locations in the lens barrel 72 such as atthe end closest to the imaging sensor, or even between the lenses 74.Furthermore, the polarizing filter 76 may be simply placed in front ofthe auxiliary imaging device.

When the imaging assembly 14 is properly installed in the insertion tube12, the auxiliary imaging device 64 of the imaging assembly 14preferably faces backwards towards the main imaging device 32 asillustrated in FIG. 3. The auxiliary imaging device 64 may be orientedso that the auxiliary imaging device 64 and the main imaging device 32have adjacent or overlapping viewing areas. Alternatively, the auxiliaryimaging device 64 may be oriented so that the auxiliary imaging device64 and the main imaging device 32 simultaneously provide different viewsof the same area. Preferably, the auxiliary imaging device 64 provides aretrograde view of the area, while the main imaging device 32 provides afront view of the area. However, the auxiliary imaging device 64 couldbe oriented in other directions to provide other views, including viewsthat are substantially parallel to the axis of the main imaging device32.

As shown in FIGS. 2 and 3, the link 66 connects the auxiliary imagingdevice 64 to the distal end 68 of the tubular body 60. Preferably, thelink 66 is a flexible link that is at least partially made from aflexible shape memory material that substantially tends to return to itsoriginal shape after deformation. Shape memory materials are well knownand include shape memory alloys and shape memory polymers. A suitableflexible shape memory material is a shape memory alloy such as nitinol.The flexible link 66 is straightened to allow the distal end of theimaging assembly 14 to be inserted into the proximal end of assembly 14of the insertion tube 12 and then pushed towards the distal end 36 ofthe insertion tube 12. When the auxiliary imaging device 64 and flexiblelink 66 are pushed sufficiently out of the distal end 36 of theinsertion tube 12, the flexible link 66 resumes its natural bentconfiguration as shown in FIG. 3. The natural configuration of theflexible link 66 is the configuration of the flexible link 66 when theflexible link 66 is not subject to any force or stress. When theflexible link 66 resumes its natural bent configuration, the auxiliaryimaging device 64 faces substantially back towards the distal end 36 ofthe insertion tube 12 as shown in FIG. 5.

In the illustrated embodiment, the auxiliary light source 70 (as well asother components) of the imaging assembly 14 is placed on the flexiblelink 66, in particular on the curved concave portion of the flexiblelink 66. The auxiliary light source 70 provides illumination for theauxiliary imaging device 64 and may face substantially the samedirection as the auxiliary imaging device 64 as shown in FIG. 5.

The endoscope 10 includes another polarizing filter 78 placed in frontof the auxiliary light source 70. The polarizing filter 78 may beattached to the auxiliary light source 70 by any suitable means such asadhesive bonding or welding.

The flexible link 66 may be encapsulated or shrouded by flexible tubing,heat-shrinkable tubing, urethanes, rubber or silicon so as to allowsmooth profile transition from the tubular body 60 to the imaging device64. This encapsulation may be translucent to allow light from the lightsource 70 to project through the encapsulation, or the encapsulation mayinclude a window section around the light source 70.

Since the main imaging device 32 and its light source 34 face theauxiliary imaging device 64 and its light source 70, the light sources34, 45 of the imaging devices 32, 64 may interfere with the opposingimaging device 64, 32. That is, the main light source 34 may shinedirectly into auxiliary imaging device 64 and the auxiliary light source70 may shine directly into the main imaging device 32, degrading bothimages.

To eliminate or reduce the light interference, the polarization plane ofthe polarizing filter 46 for the main imaging device 32 may be set at asubstantially 90° angle from the polarization plane of the polarizingfilter 78 for the auxiliary light source 70. With this arrangement, thelight, which is emitted from the auxiliary light source 70 and passesthough the polarizing filter 78, may be filtered out by the polarizingfilter 46 and may not reach the main imaging device 32. Additionally oralternatively, the polarization plane of the polarizing filter 76 forthe auxiliary imaging device 64 may be set at a substantially 90° anglefrom the polarization plane of the polarizing filters 48 for the mainlight sources 34. With this arrangement, the light, which is emittedfrom the main light sources 34 and passes though the polarizing filters48, may be filtered out by the polarizing filter 76 and may not reachthe auxiliary imaging device 64.

Moreover, to provide illumination, the polarization plane of thepolarizing filter 46 for the main imaging device 32 may be substantiallyaligned with the polarization plane of the polarizing filters 48 for themain light sources 34 so that the light, which is emitted from the mainlight sources 34 and passes though the polarizing filters 48, may passthrough the polarizing filter 46 and may be received by the main imagingdevice 32. Additionally or alternatively, the polarization plane of thepolarizing filter 76 for the auxiliary imaging device 64 may besubstantially aligned with the polarization plane of the polarizingfilter 78 for the auxiliary light source 70 so that the light, which isemitted from the auxiliary light source 70 and passes though thepolarizing filter 78, may pass through the polarizing filter 76 and maybe received by the auxiliary imaging device 64.

The desired relative orientations of the polarizing filters' thepolarization planes, as set forth above, may be achieved in any suitablemanner. For example, the polarization planes of the polarizing filters46, 48 for the main imaging device 32 and main light sources 34 may bealigned and fixed in the polarizer cap 38, and the polarization planesof the polarizing filters 76, 78 for the auxiliary imaging device 64 andauxiliary light source 70 may be aligned and fixed in the imagingassembly 14. Then the imaging assembly 14 may be rotated within thechannel 16 of the insertion tube 12 by means of its handle 62 until thepolarization planes of the polarizing filters 76,78 in the imagingassembly 14 are at a substantially 90° angle from the polarizationplanes of the polarizing filters 46, 48 in the polarizer cap 38.

The orientations of the polarizing filters' the polarization planes maybe determined and set during attachment by viewing a light with a knownpolarization passing through polarizing filters. Alternatively, thepolarizing filters may have asymmetrical shapes or other locatingfeatures so that the orientations of their polarization planes may bereadily determined.

Although the polarizing filters 46, 48, 76 and 78 are described above aslinear polarizing filters, all or some of them may be circularpolarizing filters. In one embodiment, for example, the polarizingfilter 76 for the auxiliary imaging device 64 may be a circularpolarizing filter of one orientation (such as the left hand), and thepolarizing filters 48 for the main light sources 34 may be a circularpolarizing filter of the opposite orientation (such as the right hand).Preferably, the retarders of the opposite polarizing filters 48 and 76face each other. Also the polarizing filter 46 for the main imagingdevice 32 may be a circular polarizing filter of one orientation, andthe polarizing filter 78 for the auxiliary light source 70 may be acircular polarizing filter of the opposite orientation. Preferably, theretarders of the opposite polarizing filters 46 and 78 face each other.In these configurations, the light from a light source is blocked fromthe image device facing the light source. The use of circular polarizingfilters in this configuration allows significant light reduction fromglare caused by the light sources without requiring a precise angularalignment or orientation between the two polarizing filters.

The auxiliary imaging device 64 and its light source 70 may be connectedto a control box (not shown) via electrical conductors that extend fromthe imaging device 64 and light source 70; through the link 66, tubularbody 60, and handle 62; to the control box. The electrical conductorsmay carry power and control commands to the auxiliary imaging device 64and its light source 70 and image signals from the auxiliary imagingdevice 64 to the control box.

The control box includes at least an image and signal processing deviceand a housing in which the image and signal processing device isdisposed, although the control box can be configured in any suitablemanner. The housing may include a control panel and connectors. Thecontrol panel includes buttons and knobs for controlling thefunctionalities of the control box.

The image and signal processing device may include one or moreintegrated circuits and memory devices along with associated discretecomponents. The device allows image signals from the imaging devices 32,64 to be processed for the enhancement of image quality, extraction ofstill images from the image signals, and conversion of video format forcompatibility with the display device.

The control box preferably processes the video image signal from theauxiliary imaging device 64 and transmits it to a display device such asa television or a monitor such as a liquid crystal display monitor.Still images can be captured from the video image signal. The videoimage or still image may be displayed on the display device. The displaydevice may also include textual data that are used to displayinformation such as patient information, reference numbers, date, and/ortime.

The image signal from the main imaging device 32 may also be processedby the control box in the same way that the image signal from theauxiliary imaging device 64 is processed. The images from the main andauxiliary imaging devices 32, 64 may be displayed on two separatemonitors or on the same monitor with a split screen.

The control box may further be used to adjust the parameters of theimaging devices 32, 64 and their light sources 34, 70, such asbrightness, exposure time and mode settings. The adjustment can be doneby writing digital commands to specific registers controlling theparameters. The registers can be addressed by their unique addresses,and digital commands can be read from and written to the registers tochange the various parameters. The control box can change the registervalues by transmitting data commands to the registers.

The control box may additionally be used as an interface to the patientrecords database. A large number of medical facilities now make use ofelectronic medical records. During the procedure relevant video andimage data may need to be recorded in the patient electronic medicalrecords (EMR) file. The signal processing circuit can convert image andvideo data to a format suitable for filing in the patient EMR file suchas images in .jpeg, tif, or .bmp format among others. The processedsignal can be transmitted to the medical professional's computer or themedical facilities server via a cable or dedicated wireless link. Aswitch on the control panel can be used to enable this transmission.Alternatively the data can be stored with a unique identification forthe patient in electronic memory provided in the control box itself. Thesignal processing circuit can be utilized to convert the video and imagedata to be compatible with the electronic medical records system used bythe medical professional. The processing may include compression of thedata. A cable or a wireless link may be used to transmit the data to acomputer.

During endoscopy, a technician may first install the polarizer cap 38onto the endoscope's insertion tube 12. A physician may then insert theendoscope into a body cavity through an orifice of the body. Once theendoscope is inserted, the physician may decide to use the imagingassembly 14 in order to obtain a rear-viewing image of a certain tissue.The physician may straighten the flexible link 66 of the imagingassembly 14 and insert the straightened distal end of the imagingassembly 14 into the channel 16 of the endoscope's insertion tube 12from the handle 22. The imaging assembly 14 can then be pushed towardsthe distal end 36 of the insertion tube 12. When the auxiliary imagingdevice 64 and flexible link 66 are pushed out of the distal end 36 ofthe insertion tube 12, the flexible link 66 resumes its natural bentconfiguration as shown in FIG. 2. The main imaging device 32 nowcaptures a front-viewing image, and the auxiliary imaging device 64simultaneously captures a rear-viewing image of the same area. Thephysician may then rotate the imaging assembly 14 so that thepolarization planes of the polarizing filters 76,78 in the imagingassembly 14 are at a substantially 90° angle from the polarizationplanes of the polarizing filters 46, 48 in the polarizer cap 38. Oncethe correct orientation has been established, the physician locks orfixes the orientation of the imaging assembly 14 relative to theinsertion tube 12. The physician then continues with the procedure.

The above-described embodiment is merely one of many alternativeembodiments of the present invention. In one other alternate embodiment,polarizing filters are placed over only the auxiliary imaging device 64of the imaging assembly 14 and the main light sources 34 to reduce lightinterference between them. In this embodiment, a low intensity auxiliarylight source 70 may be used for the auxiliary imaging device 64 toalleviate any bright spots that could be seen by the main imaging device32. This arrangement allows maximum light intake by the main imagingdevice 32 without light loss caused by a polarizing filter. Similarly,in another alternative embodiment, polarizing filters are placed overonly the main imaging device 32 and the auxiliary imaging device 64.These two embodiments are useful depending on the types of imagingsensors used in the endoscope, specifically their light sensitivities,resistance to blooming, and dynamic ranges, as well as depending on thetypes of light sources used in the endoscope and their illuminationintensities and/or wave length spectrums.

In another alternate embodiment, the main imaging device 32 and mainlight sources 34 may share a polarizing filter. For example, thepolarizer cap mounted on the distal end of the insertion tube may have alarge polarizing filter approximately the size of the cap end wall. Thislarge filter may have openings for the channels 16 of the insertion tube12. Alternatively, the filter may occupy only the area of the cap's endwall in front of the main imaging device 32 and main light sources 34.This embodiment allows for the orientation of the polarization plane infront of the main imaging device 32 and main light sources 34 to beprecisely orientated.

In general, a polarizing filter may be placed in a cap mounted in frontof an imaging device, placed in the lens assembly of the imaging device,or attached to the front of the imaging device. Various techniques forattachment may be used, such as ring and clamp arrangements, snap fit orplastic friction fit arrangements, or even permanent bonding.Alternatively, polarizing filters may be placed along the optical pathof the fiber optic bundles that run along the length of the endoscope,or even placed in an external light source box.

In still another alternate embodiment, a cap with one or more polarizingfilters, similar to the cap 38 shown in FIGS. 2 and 3, may be placed onthe auxiliary imaging device 64.

In yet another alternate embodiment, as shown in FIG. 6, when multipleendoscopes 80, 82, which may be considered as an endoscope assembly, arcused during a procedure, such as during laparoscopy or arthroscopy, apolarizer cap 84, 86 may be placed over one or more of the endoscopes80, 82 to reduce light interference caused by endoscopes 80, 82. In FIG.6, the endoscopes 80, 82 are inserted into a peritoneal cavity 88.Preferably, at least one of the endoscopes 80, 82 has a channel thatallows a surgical tool 90 to access the peritoneal cavity 88. In theillustrated embodiment, one or more of the endoscopes 80, 82 may have alight source. In some cases, each and every one of the endoscopes 80, 82has a light source. Similarly, one or more of the endoscopes 80, 82 mayhave an imaging device. In some cases, each and every one of theendoscopes 80, 82 has an imaging device. In one particular case, onlyone of the endoscopes has a light source, while each of the otherendoscopes has only an imaging device. In the illustrated embodiment,the polarizing filters of the same cap 84, 86 may have the same plane ofpolarization, and the polarizing filters of the different caps 84, 86may have different planes of polarization. Alternatively, the caps mayhave the same plane of polarization but a physician can rotate one ormore endoscopes to the appropriate orientations. If only two endoscopes80, 82 are used, the two caps 84, 86 may have their planes ofpolarization orientated at 90° from one another. If only threeendoscopes are used, the three caps may have polarization planesorientated at 120° relative to one another so as to provide asignificant cancellation of light interference at each endoscope.

In a further alternate embodiment, the endoscope may have orientationarrangements on both the polarizer cap and the imaging assembly suchthat the orientation between polarizing filters may be easily adjusted.One such embodiment includes a small magnet that is permanently fixed tothe polarizer cap, and a metallic element fixed to the imaging assembly.The magnet may be a rare earth magnet such as a Neodymium Iron Borontype permanent magnet. The orientation of the magnet and metallicelement is designed such that the magnetic field generated by the magnetwill attract the metallic element most strongly when the polarizingfilters are properly aligned. In this manner, when the metallic elementis in close proximity to the magnet, it will naturally be pulled by themagnet into the correct position. Furthermore, when the magnet andmetallic element come into contact, an attachment is formed whichresists change of orientation and maintains the proper orientationbetween the polarizing filters. Only when a substantial force isapplied, such as when the physician forcefully advancing the imagingassembly, will the magnetic attachment be broken, allowing the physicianto re-align or remove the imaging assembly. Alternatively, the magnetmay be placed in the imaging assembly and a metallic element may belocated on the cap. Furthermore, magnets may be used on both the imagingassembly and the cap.

In still a further alternate embodiment, the orientation featuresinclude a feature, such as a pin, rod or geometric feature, affixed toand protruding slightly away from the imaging assembly, and a feature,such as a cup and tube, on the polarizer cap that mates with thecorresponding feature on the imaging assembly. The features may be madefrom a compressive material such as rubber so that when the two featuresare engaged a substantial force is needed to break the engagement. Inthis manner, the physician would first slide the imaging assembly pastthe distal end of the insertion tube and then, under the guidance of theauxiliary imaging device, rotate the imaging assembly to achieve thecorrect relative orientation between the polarizing filters. When thecorrect relative orientation between the polarizing filters is achieved,the physician may retract the imaging assembly so that the two featuresengage and lock together. To later disengage the features, the physicianmay forcefully advance the imaging assembly.

In yet a further alternate embodiment, the distal end of the imagingassembly includes a mechanism that can fix the position of the imagingassembly in the channel of the insertion tube. Such a mechanism mayinclude the use of inflatable balloons, springs that are actuated viaguide-wires, mechanical engagement arrangements, or frictional methodssuch as large diameter compressive regions incorporating rubber or foam.

In the present application, the terms “insertion tube,” “imagingassembly” and “endoscope” are interchangeable, may have the same orsimilar meanings, and may have the same or similar features andfunctions. Different terms are used in the application for ease ofidentification and description. Additionally, such a description shouldnot be used to limit the breadth of the application. The use of“insertion tube,” “imaging assembly”, or “endoscope” merely refers topossible types of instruments in the broad field of endoscopy and theinvention may be applied to many forms of endoscopes and medical imagingdevices.

Furthermore, the configuration of one endoscope that is inserted throughthe channel of another endoscope (such as the imaging catheter beinginserted through the main endoscope as described in the preferredembodiments) can be referred to as a major-minor endoscopeconfiguration, where the larger diameter endoscope is referred to as themajor endoscope and the smaller diameter endoscope as the minorendoscope.

1-17. (canceled)
 18. An endoscope assembly, comprising: an imagingassembly including an auxiliary imaging sensor and an auxiliary lightsource, wherein the imaging assembly is configured to be at leastpartially disposed within and extendable from a working channel of anendoscope such that the auxiliary imaging sensor exits the workingchannel and faces toward a distal end of the endoscope; a firstauxiliary polarizing filter disposed over the auxiliary imaging sensor,wherein the first auxiliary polarizing filter is angulation-independentand configured to filter light from the distal end of the endoscope. 19.The endoscope assembly of claim 18, further comprising an endoscope capwith a primary polarizing filter with the opposite orientation of thefirst auxiliary polarizing filter.
 20. The endoscope assembly of claim18, wherein the first auxiliary polarizing filter includes a retarder.21. The endoscope assembly of claim 18, wherein the auxiliary lightsource is configured to illuminate a field of view of the auxiliaryimaging sensor.
 22. The endoscope assembly of claim 18, wherein theimaging assembly further comprises a second auxiliary polarizing filterthat is angulation-dependent.
 23. The endoscope assembly of claim 18,wherein the imaging assembly further comprises a second auxiliarypolarizing filter that is angulation-independent but comprising anorientation opposite the first auxiliary polarizing filter.
 24. theendoscope assembly of claim 19, further comprising an endoscope, whereinthe endoscope cap is configured to attach to a distal end of theendoscope.